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        <h2>
          <span class="refentrytitle">pvstencil</span>
        </h2>
        <p>pvstencil — 
      Transforms a pvoc stream according to a masking function table.
    </p>
      </div>
      <div class="refsect1">
        <a id="idp139794912"></a>
        <h2>Description</h2>
        <p>
      Transforms a pvoc stream according to a masking function table;
      if the pvoc stream amplitude falls below the value of the function
      for a specific pvoc channel, it applies a gain to that channel.
    </p>
        <p>
      The pvoc stream amplitudes are compared to a masking table, if
      the fall below the table values, they are scaled by <span class="emphasis"><em>kgain</em></span>. Prior
      to the operation, table values are scaled by <span class="emphasis"><em>klevel</em></span>, which can be
      used as masking depth control.
    </p>
        <p>
    Tables have to be at least fftsize/2 in size; for most GENS it is
    important to use an extended-guard point (size power-of-two plus
    one), however this is not necessary with GEN43.
    </p>
        <p>
    One of the typical uses of <span class="emphasis"><em>pvstencil</em></span> would be in noise
    reduction. A noise print can be analysed with <span class="emphasis"><em>pvanal</em></span> into a PVOC-EX
    file and loaded in a table with <span class="emphasis"><em>GEN43</em></span>. This then can be used as
    the masking table for <span class="emphasis"><em>pvstencil</em></span> and the amount of reduction would
    be controlled by <span class="emphasis"><em>kgain</em></span>. Skipping post-normalisation will keep the
    original noise print average amplitudes. This would provide a good
    starting point for a successful noise reduction (so that <span class="emphasis"><em>klevel</em></span>
    can be generally set to close to 1).
    </p>
        <p>
    Other possible transformation effects are possible, such as
    filtering and `inverse-masking'.
    </p>
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      <div class="refsect1">
        <a id="idp139877760"></a>
        <h2>Syntax</h2>
        <pre class="synopsis">fsig <span class="command"><strong>pvstencil</strong></span> fsigin, kgain, klevel, iftable</pre>
      </div>
      <div class="refsect1">
        <a id="idp139879984"></a>
        <h2>Performance</h2>
        <p>
      <span class="emphasis"><em>fsig</em></span> -- output pv stream
    </p>
        <p>
      <span class="emphasis"><em>fsigin</em></span> -- input pv stream.
    </p>
        <p>
      <span class="emphasis"><em>kgain</em></span> -- `stencil' gain.
    </p>
        <p>
      <span class="emphasis"><em>klevel</em></span> -- masking function level (scales
      the ftable prior to `stenciling') .
    </p>
        <p>
      <span class="emphasis"><em>iftable</em></span> -- masking function table.
    </p>
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                <img alt="[Warning]" src="images/warning.png" />
              </td>
              <th align="left">Warning</th>
            </tr>
            <tr>
              <td align="left" valign="top">
                <p>
        It is unsafe to use the same f-variable for both input and output of pvs opcodes. Using the same one might lead to undefined behavior on some opcodes. Use a different one on the left and right sides of the opcode.
      </p>
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      <div class="refsect1">
        <a id="idp139886080"></a>
        <h2>Examples</h2>
        <p>
      </p>
        <div class="example">
          <a id="idp139887008"></a>
          <p class="title">
            <strong>Example 712. Example</strong>
          </p>
          <div class="example-contents">
            <pre class="programlisting">
fsig    <span class="opc">pvsanal</span>   asig, 1024, 256, 1024, 1
fclean  <span class="opc">pvstencil</span> fsig, 0, 1, 1
aclean  <span class="opc">pvsynth</span>   fclean</pre>
          </div>
        </div>
        <p><br class="example-break" />
    </p>
      </div>
      <div class="refsect1">
        <a id="idp139890832"></a>
        <h2>Credits</h2>
        <p>
      </p>
        <table border="0" summary="Simple list" class="simplelist">
          <tr>
            <td>Author: Victor Lazzarini</td>
          </tr>
          <tr>
            <td>November 2004 </td>
          </tr>
        </table>
        <p>
    </p>
        <p>New plugin in version 5</p>
        <p>November 2004.</p>
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